1. Field of the Invention
The present invention relates to communication apparatuses.
2. Description of the Related Art
A Network Interface Card (hereinafter referred to as “NIC”) has been commonly used in a communication apparatus to allow the communication apparatus to communicate with another communication apparatus via a network such as a local area network (LAN). The NIC is a board connected to the communication apparatus via, for example, a bus and provides the function of connecting the communication apparatus via a network cable to the other communication apparatus.
Ethernet® is known as a typical network standard. Ethernet® protocols include 10BASE-T for a data transfer rate of 10 Mbps, and 100BASE-TX for a data transfer rate of 100 Mbps. Recently, 1000BASE-T for a data transfer rate of 1000 Mbps is also available.
In recent years, NICs that can communicate at a plurality of communication speeds, such as at 10 Mbps, 100 Mbps, and 1000 Mbps, have been proposed in, for example, Japanese Patent Laid-Open No. 2001-154763.
There has been a recent demand for a reduction in power consumption of communication apparatuses. To reduce the power consumption of a communication apparatus, the communication apparatus preferably enters a power saving mode in which, when part of the communication apparatus is not operating, power supply to that part is cut off.
However, the communication apparatus cannot return from the power saving mode to a normal power mode unless the communication apparatus is able to detect a factor relating to returning from the power saving mode to the normal power mode.
Therefore, when the communication apparatus operates in the power saving mode in which the power consumption thereof is reduced, it is preferable to supply power to a portion that detects a factor relating to returning from the power saving mode, but not to the other portions.
A NIC disclosed in Japanese Patent Laid-Open No. 2001-154763 can reduce its power consumption by reducing the communication speed when the communication apparatus operates in the power saving mode.
When the communication apparatus operates in the power saving mode, it is preferable that no power be supplied to portions other than the portion detecting the factor relating to returning from the power saving mode. However, the NIC disclosed in Japanese Patent Laid-Open No. 2001-154763 is not configured to implement such an operation.
More specifically, the NIC disclosed in Japanese Patent Laid-Open No. 2001-154763 is designed in such a manner that, in the power saving mode, power is supplied even to the portions other than the portion detecting the factor relating to returning from the power saving mode.